Process of making a ferroalloying material and product obtained thereby



United States Patent PROCESS OF MAKING A FERROALLOYING MATE- RIAL AND PRODUCT OBTAINED THEREBY.

viHenry Bruce Megill, Spokane, Wash., assignor to Chromium Mining & Smelting Corporation, Limited, Sault vSte. Marie, Ontario, Canada, a corporation of Canada No Drawing. Application June 5, 1953,

Serial No. 359,947

18 Claims. (Cl. 29182.5)

This invention relates to'a process for making a ferroalloying material and to the product produced by the process, .More particularly, the invention relates to a vacuum furnace process for making a low carbon ferroalloying material containing at least two alloying metals one of which is derived from (a ferroalloy of) the group of ferroalloys consisting of ferrochromium, ferromanganese, ferrotitanium,'ferrornolybdenum, ferrotungsten, ferrovanadium, ferrozirconium and ferrohafnium and the other of which is obtained from a material containing an 'oxide ofnickel or cobalt. Mixtures of the ferroalloys and of the metal oxides may, of course, be employed in the process. 1

The invention also relates to a ferroalloying material that is especially useful in making alloy steels and other ferrous alloys.

An object of the invention is to provide a process for the production of new ferroalloying materials including in addition to iron at least one of the metals nickel and cobalt and at least one of the metals chromium, manganese, ftitanium, molybdenum, tungsten, vanadiumjz'irconium and hafnium.

A further object of the invention is to provide a process for the production of the ferroalloying materials described in the immediately preceding paragraph that involves a vacuum furnace treatment thatlends itself to:

simple, efiicient and economical practice."

Another object of the invention is to provide a ferro alloying material that is low in carbon andhence is highly desirable for use in the manufacture of high alloy steels.

Another object of the invention is to provide 'an' alloying product-that is readily soluble in steel baths whereby the alloying materials. are easily' incorporated in steel melts in open hearth furnaces.

her .q jss st Pro i a so po i te o ll yin material whereby two or more alloying metals may be added to a steel bathin a single operation. U

Another object is to provide aproduct that maybe reduced to powder. compounded with other materials to form an exothermic product that may be added to steel in the ladle. Ex-

othermicity may be supplied, for example, by a. silicothermic reaction in which the reactants may be silicon and sodium nitrate.

The foregoing and other aims, objects and advantages of the invention as may appear or be inferred from the following text are realized in a process for making a ferroalloying material which comprises reacting in contact with each other,'( 1) a metal carbide such as medium to high carbon-containing ferroalloys of chromium, manganese, titanium, molybdenum, tungsten, vanadium, zirconium or hafnium or mixtures thereof or inter-alloys of the same with (2') a material containing substantial amounts of nickel oxide or cobalt oxide or mixtures thereof. The reaction.- is carried out by heating the The powdered material may; be

2,763,918 Patented Sept. 25, 1955 the reaction is complete a metallic residue remains in the confined zone that is low in carbon and includes nickel and/or cobalt'plus one of the metals chromium, manganese, titanium, molybdenum, tungsten, vanadium, zirconium and/or hafnium in addition to iron. The product also may containsmall amounts of silicon and minor amounts of oxide impurities such as SiOz, CaO, MgO, A1203 and'the'like.

In carrying out the process, the ferroalloy that contains carbon is comminuted as by grinding to fine particle size. The particle size of the material may be reduced to a point where substantially all of the material passes through a mesh screen with a substantial portion of the grind being small enough to pass a 200 mesh screen. The metal oxide, such as nickel oxide,-if not already of sufiiciently fine size is reduced as by grinding so that most of the material passes through a 100 mesh screen.

Taking into account the carbon content of the ferroalloy and the nickel oxide and the purity of the nickel oxide-containing material, a mixture of the finely ground ferroalloy and nickel oxide-containing material is prepared wherein theamount of nickel oxide is so calculated with respectto the quantity of ferroalloy that sufiicient oxide is provided to oxidize all of the carbon of the ferroalloy to carbon monoxide. A slight excess of nickel oxide may be incorporated in the mixture and sufficient excess may be incorporated to provide for oxidation of the silicon of the ferroalloy plus other minor ingredients capable of oxidation. v

It is desirable to form the mixture into agglomerates or briquettes and for this purpose a binding agent is incorporated with the mixture. Any suitable organic or inorganic binder may be used. It has beenfound that a binder known as Goulac is suitable. Goulac is a powdered binder derived from waste sulphite liquor and includes lignin sulphonate as a principal binding ingredient. The amount of binder that is used may be about 2% by weight of the mixture, but amounts of binder ranging from /2.% to 4% may be used. It is desirable to use a minimum quantity of binder and the amount of any particular binder that is employed is readily determined by simple experimentation.

The mixture is formed into agglomerates as by subjecting the mixture to a roll-pressing operation to provide agglomerates of proper size. The size of the agglomerates may range from one-half inch to two or three inches more or less. After pressing, the agglomerates are dried, if necessary, ,at a low to medium drying temperature.

Where Goulac is used as binder, the dried agglomerates may be heated to a somewhat higher temperature of say 450" C. to partially decompose and drive off part of the binder from the agglomerates. This operation is performed without vacuum so that the gaseous products arenot carried through the vacuum system.

The decarburizing reaction is carried out in a confined zone such as is provided in the interior space of a vacuum retort. Suitable vacuum pumping equipment is provided to maintain the necessary low pressures in the retort. I

Depending upon the size of the vacuum retort, a

charge of agglomerated reaction mixture of suitable size is introduced into the retort and the retort is thereafter closed and placed under vacuum. If not already hot,

3 a the retort is heated to the desired reaction temperature and kept at reaction temperature for the time necessary to decarburize the mixture under the vacuum conditions imposed. It is desirable thatthe vacuum system have ample capacity to withdraw the gasesfevolvediftlfejr action at a rapid"enough rate to niaintaifi tfi'e inthe reaction vessel at" suitablejloiv 'vamesg' It, desirablethatthe pressure the va'cuurrireto'r be 'rdu as rapidly as possible'to about 401050 mm; of ji erur i It is 'furtheridesirable that the final pressnrhhe m vacuum retort wherithe las'tincremeiits ofcarb n ma oxide are beingwithdrawn be r'edu cedito a val o f the order' offlIS O microns of iinercprjorlssLt Temperatures er the order"ofllZODf'fCf are suitable. to promote the' decarburi'zation fof tlieijmiktu e1 ever;temperatures"rangingfrorn 100 C to' 14' may be employed.

The time or reaction will vary widely depending upon the agglomerates employeda'nd t h f h w 1 time to heat-up and out-gastric one hour to dafor two; sures of "cute-sonar; may few hours tof several days.

itflisdesirable to cool: residue after th e rea ion is complete and before exposing th residue' to th I phere, this in order to'eliminatdor m1 n'rize oxid of theue siduel Preferably" tlle re tor t iand residue. are cooledtofatemperature bell also "4091C. ljiiorelthe; retort is opened and the reSidiie e posed 'tothe 'a'tr nq phere. Below about 400 C. the residue may b r from; the "retort and cooled" in the a wr undergoing excessive'oiiidation. t

The residue from the vacuum furnace operation in general maintains its ,agglonreratdforrnj 'Altho soine shrinkage does occur, thi briquettes retain theirioriginal 'fis'a shape without breaking into finer pieces or particles which; would not? be des rable in the final product. The agglonnerates are"sintered, porous, dense 'aggregatesfof finely divided particles that are lowin carbojrrarid, in ad ditioni to iroiiifrorrl'the terror-alloy they contain theja lloyrn a1 '40 or metalsjsnchhs chromium oftheferrpalloy ma a '1' metal such as nickel and/or cobalt oftheoigidant, The residue'ag'gloirierates 'arehigh in metallicjco nt, low

in slagconteiitf and are low to extremelylow mi n-pen conterit. Carbon fan'alyses less tha n ;o.1 o%%jare* readilyattainedfand carbomanalyses fasi 1 w as: OIOIj to QQZfZg, may be attained. i The residue 'agglornerates may be incorporated-direct: ly mm steel for rheriianafaaureqrano'y open heartHor electric furna'c Although the residue"agglorherates areinon ordinary handling and shipment; they a r friable 'that"they' mayflbe' c'otiv d" terial by conventional methods may be made"intoanekotherrriic coffipo slt tionof powdered ferrosiliconand sodiuh'j' nitrat I proportional Anfotherdesiredexother I may include the powdered alloying mat tion. Such exothermic mixtures are erm for makingd'adle" additions"t o steel. Typically, 'tl'ie felrr'oal loyingjnatefials of the invention. are in theform of emerge-56mm; aen'saa re atgaf v finely divided particles"containing" a: metal of ale consisting'of'niclgel a'nkl"cob"alt"in amoui's rangngffro I 20% to%, a'rnetal'of the'grou'p cons t'i mium, manganese, titanium," molybden in, vanadium, zirconium andhafniuni in M from-25% to %,3a5t1cai oir fi'in uat w 0.01% to 0.15%, the"alloying metal cont aggregates being greater 45%,"the balane being substantially all iron excepffor" incidental metal metallic oxide constituents.

1h Q15? @31 t i ii -afia? qnth isl eaibu t1on of itheheaction mix t ure, it is important that, a

isli-P rsaai q t sha e? mn cssunesllcula bet/.15

w en-t final carbon analysis is tool 1 above course of the reaction to its final end value of 150 'microns, more or less. By assuring continuous withdrawal of carbon monoxide from the aggregates in the vacuum retort, the pores of the aggregates are kept open and the final desired low carbon analysis is realized. By mainraining on muons .fl w ofw a f nyihe q qrt agtl qn a f fie 'iv amm iefiai el L-r i qlm 'On the" other" hand, if'gas is not continuously withdrawn, thrgughout the, reaction pcriqd, uthetipores tofic the aggregates, are-likely;ttotibecomeasealed offfand there; after the. reaction .rateuis reduced to a low-order and the The principal rea ctlonrthat take he following equawithdrawn."Ih 'this'stage f the reactio'n the chrome-of 7 the 'chf'o'mic oxid'e is 'r'dilc ed to them'e tallicstate; t reaction were, F9 bef ats al-i tj a a t n The "invention will 'be described with greater par ticu larity in the following detailedergamples, a

Eimmple l 2?ar alsanrl ali i the awaken? a i l wsza (IL'High Carbon Eerrochrominm; Percent Cr 53104 Thetintimateomixturehis briquetted in a Komarek-Greaves; RotaryiPress t'o ,pi'ovide.pillow bl'eksmeasuring approxi-- matelylil..xi li'ix Z W-The greenblocks aredriedfima l warm oven at C. for a period of afew-minutes to-- fomrr ar dried; s'kinv theneont that ena'bleihe.blocksdobe hand1ed.-.witliout vbreakage in subsequent-furnace operations l'l-"heedried blocks; are then preheated ito -450 ---"O. andmheld- ;at ,thisetemperature. rerza period :of from 1 to- I 2 hours .totcornpletertlizdnyinglof tthelbloeksandtoiclrivea ofhthetrbulklofiatlie iGou lac. T- T hegbrique tted blooks are charged otora. vacuum tretortutuberl-lwhich tis :subsequentlyt raised-to lfanaoperatihge temperature -of v 12003126. v: Prior-l to heating;.the retortuis sealeduanddvac'uumflis applied Thereaiterrtheicharge. is, .heatedeifora. period of aten i hours, theiyacuuni being maintained "throughout the mac tion pcriodtbeginning atl4.5 of tmercury iandlvc'on-n i uouslywbeing rreducedeuntil rat Jhflnfifld of iheureacjionm.

areas-1s period of pressure is 80 microns and gas'evolution issub stantially nil.

The retort is allowed to cool for a'period of 24, hours Percent Cr 34.98 Ni 34.95 Fe 22.84 Total Si as SiOz 5.86 C 0.027

Example II The materials employed in this example are the same as those used in Example I except that cobalt oxide, C00, is substituted for nickel oxide. The materials are mixed in the following proportions:

Pounds HC FeCr 100 C00 i 70 Goulac 3 .5 Water 2.6 Glucose 2.0

Themixture is briquetted, dried and subjected to a vacuum furnace treatment in the same manner as the mixture of Example I. The vacuum furnace product is similar in appearance to that obtained in the immediately preceding example. 149 lbs. of vacuum furnace residue is obtained having the following analysis:

Percent Cr 34.90 Co 34.99 Fe 23.06 Total Si as SiO 5.57

Example III This-example illustrates large scale production of low carbon iron-chromium-nickel alloying material.

The materials employed are as follows:

(1) High carbon ferrochromium: Percent Cr Y 53.04' Fe 32.24 Si 4.34 C 7.01 (2) Nickel oxide: Percent NiO 99+ (3) Goulac.

The high carbon ferrochromium and the nickel oxide are ground to pass a 100 mesh screen with 70% through a 200 mesh screen. v

The materials are intimately mixed in the following proportions:

Pounds HC FeCr 6,880 NiO 4,820 Goulac 241 Water 179 The mixture of ingredients is briquetted, dried and heated to about 450 C. to drive off most of the binder and all of the residual water.

The dried briquettes are charged into a vacuum retort internally heated by electric resistance elements, the retort being at room temperature. The retort is closed and vacuum is applied. The heating elements of the retort' are energized and the charge comes up to a temperature 4 of 1200". Chin 24 hours at which timethe pressure within the retort is 2,000 microns. The furnace temperatureis maintained at 1200 C. for an additional period of 106 hours; the furnace pressure is still 2,000 microns at the- At the end of 46 hours the furnace end of 26 hours. pressure is-'800 microns. The furnace pressure drops to 250 microns at the end of 75 hours and to 50 microns at the end of 94 hours. A pressure of 50 microns is maintained in the furnace until the power is cut off at 106 hours. Thereafter the furnace is allowed to cool for an additional period of 95 hours and is opened to the atmosphere at a temperature of 320 C. and discharged.

The residue is in the form of the original briquettes that have shrunken in volume to approximately one-half of the volume of the briquettes as charged. They have a brightmetallic luster, are hard and dense and have a microscopic, porous appearance.

The vacuum furnace residue weighs 10,000 lbs. The

residue has the following analysis:

Percent Cr 35.14 Ni 34.89 Fe 23.24 Total Si as SiO 5.03

Example IV This example is typical of the production of a low carbon iron-manganese-nickel alloying material from high carbon ferromanganese and nickel oxide.

The materials are as follows:

(1) High carbon ferromanganese: Percent Fe 7 11-.47 Si 0.235 C 6.87

(2) Nickel oxide: Percent NiO 99+ (3) Goulac.

After grinding the high carbon ferromanganese and nickel oxide to pass a 200 mesh screen, the materials are mixed as follows: 1

HC FeMn 100 MO v 44 Goulac V 3 Water a 2 The mixture of ingredients is briquetted and'driedf" The dried briquettes are placed in a vacuum retort for a. period of 12 hours at a temperature of 1200. C. under an initial vacuum of 500 microns of mercury and final vacuum of 60 microns of mercury. At thefendof this period, gas evolution has subsided to a very low value. 1". The retort is cooled and the contents discharged. The" residue weighs 131 lbs. and has the following analysis:'

Percent Mn -65.30 Ni 25.65 I Fe 8.50

Si as SiOz 0.46

/ The residue is metallic, porous and hard.

From the foregoing description it will be seen that the present invention provides a very useful process for producing low carbon ferroalloys that find ready application I in the production of alloy steels. 1

I claim:

1. A process for making a three-metal furnace additive for use in making stainless steels which comprises reacting in the solid state a material containing a substantial proportion of a metal oxide selected from the group ,1 consisting of nickel, oxide ,andcobalt oxide inintimate Pounds idsiwntai lastma atia a a substantially all in the In zone under conditions of low absolute pressure to-a tem- 25 I gxerature below the'point ofsubstantialfusion of amma terials and fora timeis'ufiicient to efi ect reaction between 1 v l l duedow incanbomineluding theanetal of the-metaL-oxid' containing-material andthe meta1s= of-the ferroalloy sub 1 tc nta aiast b tan im e lers o he it ti-i t a h me al X ;contaminstma et ala n t t er 9 he metal t-he zone,

w in carbon includ l residue lo 'tive fiorglse in making stainless steels containing irom Zfi nickeiand chromium which comprises reacting in the solid gkeloxidewith ferrochromium containing a sub- Tal'ii()lll'1 tf0fCElI'bOEYbY heating anintirnate mixture of s a gkniekel oxide andsa'id ferrochromiunr in a confined 1 Y the nickel oxide and theferrochromium withsubstantial stantial oxidation of {the carbon of the ferrochromiurn to 7 an oxide of carbon} and withcl awing the qxide of carbon] fonned in the reaction from said-confined'zone; whereby i0fl/i6ld5fi-I'6Sldll6 low imcarbpn-andqincluding metallict j P o t. lathteeanetal f naceaddL a5 er nn makingrstainless;.s elsscnt ngirqmis I sfans htotniutnlwhicbee umrisesteasti nseinlhastfl l state cobalt oxide with ferrochromiurn containing asub stant al amount of carbon by heating an intimate mixture a of said cobalt'oxide and jsaid ferrochromium in con- 40 fined zone under conditions of low absolute pressure to a of c on ptm iinthereast Qm. dsonfi etl 9.

tall ng rPPt sba t. and t r ws.

A BIQQ JP; s ak n a hrsszmetel .fuma s xa i-t .50 or, s hm lk' sus ainlssw s s 9 i e., r i iflfil g. ll il fi i QPzSE EPE ES r act n i lth n l t to n tslt ox w t i tqm nsan e c n nin A a w ttialamwn iq ts t sn b l et a intimate atsr 9 s idlnisks ug ids andr s rf r s tls in a fiastlamsynda s sl ienaq wt hts ut 93 1 to a temperature below the point of substantial fusion of said tma terials and for a time suflicient to effect reaction ween? th .nickelloxide.a d.t qcfertotuan aneseww h s tantiall tsub t esett a... l of asthma tanned. l. .ea t 9. from. sa sisztmfinetl 29 9 whereby to yield a residue low in carbon and including metallic iron, nickeland manganese.

5. A process for making at three-metab'furnace; additiverfor use in makingstainless steelswhich comprises reacting in the solid state arnaterial containing-a substan--- tial proportion of nickel oxide in intimate contact with a ferroalloy material containing a substantial amount of 70:;

1 the ferroalloy in themetaliic state.

- posit-e alloys thereof by heating said materials in a con tiye foi use i teiss tiezt sime allieinisltslaand isnbstantials datica offthe carbon of the ferroalloy to an oxide of carbonggan wine;thaio dd t fi-s r enst rmedin-thetreasflou' .f fina r ily elizaametal is: i due l w i c bon.tint udiaan eke and the imstalstn -aAt-p y ss fon ak n r t tee-meta wf mataedd e I rusei -tmakin sta nlesstste ls i h,e mpt sesre etin ti t tsolidntateratmaterialrwnt in ta bs anm tial proportion of a metal oxide selected;rom;the tgrqu consisting of nickel oxide and;lcobalt oxide idinti'rriage eontaetgwit-h a ferroalloy material containing a substantial l amount of carbon'sel'ected from ferroalloys of the groupu 7 consisting of ferrochromium, ferromanganese, -ferr'oti-; tarr m,-'-ferromolybdenum, ferrotungsten, ferrovanadium ferrozirconium; ferrohafnium, and riiixturesrg 511,51 530m,

fined zone at'ia temperaturebelow the point of substantial "fusion of said materials of 1frQ l gl00D (3; to 1400 0., atv a pressure o fabout 150 microns'of mercury at the end of the iee tctiogn period \and for-a"timqsufficient toefiect reac tio n betweenthemetaioxide-containing; inaterialand the ferroailoy with substantial reduction-ofEthemetalpf thc metal oxide to themetallic state andsubstantialoxidation it ,ofthe earbon of. the ferroalloy toan oxide'of carbon, and I "Withdrawingthemxide"ef-carbon-formedaintheqeactionfrom: said it confined zone-whereby- :to-y-ield a-metallic res stantially allin themetallic-statem A p ess akin'g stainless steels;containing 111.211,, I v n ql fanda-shrqmit m which QQ PfiS St-WECMEV n I lidfi ate-tnickelt e.w hzi oehwmium sont ini a ls stx ia tamwnm ,c r n; whe t s an tint mataniix "ture of said nickellgxide andisaidierrochromiuna mam-g fined zpne at a temperature below the point of substan tial ius n'of said materials of from 1000" C. to 1400 C i at af-p 'sfire'of about 150 microns'of mercury at the en of the rt-eaction period and for a time suiiic'ient to efiect' Weaction between the nickel oxide and the :f e'rrochromiuj witlr s ubstantial reduction of the nickel oxideto metallic nickel and substantial oxidation of the carbonof the ferrochromium to an oxide of carhomaand withdrawing the oxideof carbon formed in the reaction from said confined-zone;- wherebysto yield'i-aresiduelowin carbon-and including metallic-'iron nickeland chromium;

8. A ferroalloying-furnace'additive=in-the-form-of fineyid sidsd largely ed -in tt clest-te ch.c mpris ng a:

e rc .tthensrqyn.s nsistin m 9 k and ian x a l etq fi PfiI ZQP l an in ltr 20% to 5.

a me a Q th l tqsn s st 9 h m m nes titanium molyddenum, tungsten, anadium, zirconium, hafniym and mixtures thereof in amounts ral gl lg from 25 7;;119 65%, carbon in amounts ranging from 0.Q1% to l 55;0.15%, the alloying metal content of said aggregat e being greater than the balance being substantially all iron exception incidental metallic and metallic oxide -constitu-- ents.--

9. A fier roalloying furnace additive in the form-of a ni kgl 1go sintered 'porous, dense-aggregate of finely divided largely unfused particles each comprising nickel in amounts-rang ing f rqm 20% to chromium in amounts ranging I from; 25 -to car-bon in-- amount-sranging ---from-= l 0.01% to'O; 1-5 the balance-being substantially allirony stituents. 10.1: Atfet oal oy nsfu nace-a d ive nl f rm of a i te ed; pon u nd nse a ega e o fi e y v ded la ge y: in unfused particles each comprising cobaltinamounts range-r. ing,=from;:20% to 50%;; chromium in'amountsranging from 25%"1to;65%,:ccarbon in amounts :rranging from-" 0.01% -to 0.l5%'; 'the balancebeingsubstantially all-irons: except. fQIniHCidCHtfl metallic and metallic'g oxide con-1;- stituentsm t; 11;; A ferroallgying .tfurnace, additive-in zthe,;form of.;a

m kin ,meemaamutncawas I l sintered, porous, dense aggregate of finely divided largely unfused particles each comprising nickel in amounts ranging from 20% to 50%, manganese in amounts ranging from 25% to 65%, carbon in amounts ranging from 0.01% to 0.15%, the balance being substantially all iron except for incidental metallic and metallic oxide constituents.

12. A ferroalloying furnace additive in the form of finely divided, largely unfused particles each comprising nickel in amounts ranging from 20% to 50%, chromium in amounts ranging from 25 to 65%, carbon in amounts ranging from 0.01% to 0.15%, the balance being substantially all iron except for incidental metallic and metallic oxide constituents.

13. The method of introducing nickel into a steel melt which comprises the steps of reacting nickel oxide with ferrochromium having a substantial percentage of carbon therein to produce an iron-chromium-nickel residue in the solid state, and of adding this residue to molten steel.

14. The method of introducing nickel into a steel melt which comprises the steps of reacting nickel oxide with ferrochromium having a substantial carbon content in a vacuum furnace, the oxygen in the oxide being sufiicient to combine with substantially all of the carbon, to produce a low carbon chromium-nickel-iron residue, of agglom- .erating the residue, and of charging the agglomerate to the steel furnace.

15. The method of adding nickel or cobalt to a steel melt which is to contain at least one other metal in addition to iron in its final specification which comprises the steps of first incorporating the nickel or cobalt as a component of an alloy containing the other metal, and then adding this alloy in its solid state to the steel melt.

16. The method of making a steel containing in addition to iron one metal of .a first group of nickel and cobalt, and one or more metals of a second group consisting of chromium, manganese, titanium, molybdenum, tungsten, vanadium, zirconium, and hafnium, which comprises an initial step of reacting the metal or materials of the second group at temperatures close to but below their melting point under comparatively high vacuum conditions with the oxide of the metal of the first group to produce an intermediate product composed of metals of both groups with carbon below 0.2%, and of then adding this product to a steel melt.

17. The method of making a chromium-nickel steel which comprises an initial step of reacting nickel oxide with high carbon ferrochromium at temperatures close to but below their melting point under comparatively high vacuum conditions to produce an intermediate product consisting essentially of metallic iron, chromium and nickel with carbon below 0.2%, and of then adding this intermediate product to a steel melt to produce a chromium-nickel steel of exact metal proportions.

18. A ferroalloying material in the form of a sintered, porous, dense aggregate of finely divided particles comprising metallic chromium, nickel, and iron with negligible metallic oxides and oxide constitutents, the chromiumnickel ratio being l.52.5 of chromium to 1 of nickel.

References Cited in the file of this patent UNITED STATES PATENTS 1,059,709 Byrnes Apr. 22, 1913 2,040,566 Rohn May 12, 1936 2,107,122 Laise Feb. 1, 1938 2,170,158 Rennerfelt M Aug. 22, 1939 OTHER REFERENCES Chemistry, a Textbook for Colleges, by McPherson, Henderson, Mack and Fernelius, published by Ginn and Co. (Copy in Div. 70.) 

1. A PROCESS FOR MAKING A THREE-METAL FURNACE ADDITIVE FOR USE IN MAKING STAINLESS STEELS WHICH COMPRISES REACTING IN THE SOLID STATE A MATERIAL CONTAINING A SUBSTANTIAL PROPORTION OF A METAL OXIDE SELECTED FROM THE GROUP CONSISTING OF NICKEL OXIDE AND COBALT OXIDE IN INTIMATE CONTACT WITH A FERROALLAY MATERIAL CONTAINING A SUBSTANTIAL AMOUNT OF CARBON SELECTED FROM FERROALLOYS OF THE GROUP CONSISTING OF FERROCHROMIUM, FERROMANGANESE, FERROTITANIUM, FERROMOLYBDENUM, FERROTUNGSTEN, FERROVANADIUM, FERROZIRCONIUM, FERROHAFNIUM, AND MIXTURES AND COMPOSITE ALLOYS THEROF BY HEATING SAID MATERIALS IN A CONFINED ZONE UNDER CONDITIONS OF LOW ABSOLUTE PRESSURE TO A TEMPERATURE BELOW THE POINT OF SUBSTANTIAL FUSION OF SAID MATERIALS AND FOR A TIME SUFFICIENT TO EFFECT REACTION BETWEEN THE METAL OXIDE-CONTAINING MATERIAL AND THE FERROALLOY WITH SUBSTANTIAL REDUCTION OF THE METAL OF THE METAL OXIDE TO THE METALLIC STATE AND SUBSTANTIAL OXIDATION OF THE CARBON OF THE FERROALLOY TO AN OXIDE OF CARBON, AND WITHDRAWING THE OXIDE OF CARBON FORMED IN THE REACTION FROM SAID CONFINED ZONE, WHEREBY TO YIELD A METALLIC RESIDUE LOW IN CARBON INCLUDING THE METAL OF THE METAL OXIDE-CONTAINING MATERIAL AND THE METALS OF THE FERROALLOY SUBSTANTIALLY ALL IN THE METALLIC STATE.
 8. A FERROALLOYING FURNACE ADDITIVE IN THE FORM OF FINELY DIVIDED LARGELY UNFUSED PARTICLES EACH COMPRISING A METAL OF THE GROUP CONSISTING OF NICKEL AND COBALT AND MIXTURES THEREOF IN AMOUNTS RANGING FROM 20% TO 50%, A METAL OF THE GROUP CONSISTING OF CHROMIUM, MANGANESE, TITANIUM, MOLYDDENUM, TUNGSTEN, VANADIUM, ZIRCONIUM, HAFNIUM AND MIXTURES THEROF IN AMOUNTS RANGING FROM 25% TO 65%, CARBON IN AMOUNTS RANGING FROM 0.01% TO 0.15%, THE ALLOYING METAL CONTENT OF SAID AGGREGATE BEING GREATER THAN 45%, THE BALANCE BEING SUBSTANTIALLY ALL IRON EXCEPT FOR INCIDENTAL METALLIC AND METALLIC OXIDE CONSTITUENTS.
 13. THE METHOD OF INTRODUCING NICKEL INTO A STEEL MELT WHICH COMPRISES THE STEPS OF REACTING NICKEL OXIDE WITH FERROCHROMIUM HAVING A SUBSTANTIAL PERCENTAGE OF CARBON THEREIN TO PRODUCE AN IRON-CHROMIUM-NICKEL RESIDUE IN THE SOLID STATE, AND OF ADDING THIS RESIDUE TO MOLTEN STEEL. 